U.S. patent number 5,130,196 [Application Number 07/591,508] was granted by the patent office on 1992-07-14 for conjugate fibers and formed product using the same.
This patent grant is currently assigned to Chisso Corporation. Invention is credited to Hiroaki Nishio, Takeshi Noma.
United States Patent |
5,130,196 |
Nishio , et al. |
July 14, 1992 |
Conjugate fibers and formed product using the same
Abstract
Easily processable, polyolefin hot-melt adhesive conjugate
fibers which are unnecessary to apply any oiling agent at the time
of spinning and drawing steps, and a formed product such as
non-woven fabric, filter for water treatment, etc. obtained by
heat-treating the conjugate fibers are provided, which conjugate
fibers comprise polyolefin hot-melt adhesive conjugate fibers
composed of two different kinds of polyolefins having different
melting points by 20.degree. C. or more and constituted so that the
lower melting polyolefin can occupy at least one portion of the
fiber surface, the lower melting polyolefin having monoglyceride of
12C or more fatty acid in 3 to 10 weight % incorporated
thereinto.
Inventors: |
Nishio; Hiroaki (Moriyama,
JP), Noma; Takeshi (Moriyama, JP) |
Assignee: |
Chisso Corporation
(Nakanoshima, JP)
|
Family
ID: |
17304808 |
Appl.
No.: |
07/591,508 |
Filed: |
October 1, 1990 |
Foreign Application Priority Data
|
|
|
|
|
Oct 2, 1989 [JP] |
|
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1-257326 |
|
Current U.S.
Class: |
428/373; 428/198;
428/375; 524/315; 524/318; 442/365; 428/374; 428/394; 442/362 |
Current CPC
Class: |
D01F
8/06 (20130101); Y10T 428/2967 (20150115); Y10T
442/642 (20150401); Y10T 428/2929 (20150115); Y10T
428/24826 (20150115); Y10T 428/2931 (20150115); Y10T
428/2933 (20150115); Y10T 442/638 (20150401) |
Current International
Class: |
D01F
8/06 (20060101); D02G 003/00 () |
Field of
Search: |
;428/373,374,375,394,296,198 ;524/318,315 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lesmes; George F.
Assistant Examiner: Pawlikowski; Beverly A.
Attorney, Agent or Firm: Fay, Sharpe, Beall, Fagan, Minnich
& McKee
Claims
What we claim is:
1. Hot-melt adhesive conjugate fibers composed of two different
kinds of polyolefins having different melting points, the lower
melting point polyolefin having a melting point of at least
20.degree. C. less than the higher melting point polyolefin and
constituted so that the polyolefin having the lower melting point
can occupy at least one portion of the fiber surface, said
polyolefin having the lower melting point having monoglyceride of a
fatty acid of 12 carbon atoms or more at 3 to 10% by weight of the
lower melting point polyolefin component incorporated
thereinto.
2. Hot-melt adhesive conjugate fibers according to claim 1, wherein
said polyolefin having the lower melting point is selected from the
group consisting of high density polyethylene, low density
polyethylene, linear low density polyethylene and ethylenevinyl
acetate copolymer.
3. Hot-melt adhesive conjugate fibers according to claim 1, where
the polyolefin having the melting point higher than said polyolefin
having the lower melting point by 20.degree. C. or more is selected
from the group consisting of propylene homopolymer and copolymer
composed of propylene and copolymerizable components consisting of
ethylene or butene-1.
4. Hot-melt adhesive conjugate fibers according to claim 1, wherein
said monoglyceride of a fatty acid is selected from the group
consisting of glycerides of lauric acid, stearic acid and oleic
acid.
5. Hot-melt adhesive conjugate fibers according to claim 1, wherein
said conjugate fiber is obtained by conjugate-spinning said two
kinds of polyolefins to form a side-by-side conjugate fiber or a
sheath-and-core conjugate fiber so that the polyolefin having the
lower melting point having the above monoglyceride incorporated
therein can occupy at least a portion of the fiber surface
continuously in the length direction.
6. A formed product obtained by heat-treating the fibers as set
forth in claim 1 at a temperature the same as the melting point or
higher of said polyolefin having the lower melting point and at a
temperature lower than the melting point of the other polyolefin
having the higher melting point, and having the contact points of
the fibers fixed by melt-adhesion of said polyolefin having the
lower melting point.
7. Hot-melt adhesive conjugate fibers according to claim 1, wherein
a ratio of the high melting point polyolefin to the low melting
point polyolefin is in the range of 30/70 to 70/30.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to hot-melt adhesive, conjugate fibers
composed of polyolefines and a formed product using the same. More
particularly, it relates to easily processable fibers needing no
oiling agent applied at the spinning and drawing steps thereof, and
formed products using the same such as non-woven fabric, filter for
water treatment, etc. obtained by heat-treating the fibers.
2. Description of the Related Art
Formed products obtained by heat-treating hot-melt adhesive,
conjugate fibers consisting of polyolefins having different melting
points such as a combination of polypropylene with polyethylene,
etc. and fixing the contact points of the fibers by melt-adhesion
of the low-melting component, have superior mechanical properties
and chemical resistance. Thus, they have been used for
water-treating filter or non-woven fabric in various fields. In
general, fibers composed of thermoplastic resins having a
surfactant coated thereon as an oiling agent in order to prevent
the friction and static charge of the fibers at the time of
spinning or drawing, carding and the like steps, but the surfactant
remains in formed products prepared using such fibers. Thus, when
such products are used for water-treating filter, there have been
raised problems that a high concentration of the surfactant exudes
out into the resulting filtrate at the initial period of its use to
cause bubbling in the filtrate and particularly in the field of
foods, contamination by the surfactant occurs.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an easily
processable hot-melt adhesive conjugate fibers capable of affording
a formed product, preventing it from exuding-out of surfactant,
while retaining superior processability at spinning, drawing,
carding and the like steps.
Another object is to provide a formed product using the above
hot-melt adhesive conjugate fibers.
The present inventors have made extensive research in order to
achieve the above-mentioned objects, and have found that when
polyolefin hot-melt adhesive conjugate fibers composed of at least
two polyolefin components having different melting points are
prepared, monoglyceride of a fatty acid of 12 carbon atoms or more
in 3 to 10% by weight is incorporated into the polyolefin having a
lower melting point and conjugate-spinning is carried out so that
the polyolefin having a low melting point can occupy at least one
portion of the resulting fiber surface, to achieve the aimed
objects, and have completed the present invention.
The present invention has the following constitutions:
(1) Hot-melt adhesive conjugate fibers composed of two different
kinds of polyolefins having different melting points by 20.degree.
C. or more and constructed so that the polyolefin having a lower
melting point can occupy at least one portion of the fiber surface,
said polyolefin having a lower melting point containing
monoglyceride of a fatty acid of 12 carbon atoms or more in 3 to
10% by weight incorporated thereinto.
(2) A formed product obtained by heat-treating conjugate fibers as
set forth in item (1) at a melting point or higher of said
polyolefin having a lower melting point and at a temperature lower
than the melting point of the other polyolefin having a higher
melting point, and having the contact points of the fibers fixed by
melt-adhesion of said polyolefin having a lower melting point.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
As the polyolefin having a higher melting point in the present
invention, usual crystalline polypropylene may be used. For
example, propylene homopolymer, copolymers composed mainly of
propylene and containing copolymerizable component(s) such as
ethylene, butene-1, etc. and mixtures of thereof may be used.
As the polyolefin having a lower melting point in the present
invention, a polyolefin having a melting point lower by 20.degree.
C. or more than that of the above polyolefin having a higher
melting point such as high density polyethylene, low density
polyethylene, linear low density polyethylene, ethylene-vinyl
acetate copolymer, etc., may be used.
If the difference between the melting points of the two kinds of
polyolefins is less than 20.degree. C., the tolerable range of the
heat-treating temperature at the time of production of the formed
product becomes narrow.
As the monoglyceride of a fatty acid to be incorporated into the
polyolefin having a lower melting point, used for the hot-melt
adhesive conjugate fibers, monoglycerides of lauric acid, stearic
acid, oleic acid, etc. may be exemplified and they may be used
alone or in admixture. If the quantity of the monoglyceride
incorporated into the polyolefin having a lower melting point is
less than 3%, the resulting hot-melt adhesive conjugate fibers have
a high friction to cause troubles such as twining around the rolls
at the time of spinning and drawing steps and inferior passage
through card due to static charge, while if the quantity exceeds
10%, the melt-spinning of the hot-melt adhesive conjugate fibers
will be inferior. Therefore, satisfactory spinning is
impossible.
In order to incorporate the monoglyceride into the polyolefin
having a lower melting point, any conventional methods are employed
such as blending, kneading, etc., which are easily conducted by an
extruder, for example.
The hot-melt adhesive conjugate fibers of the present invention are
obtained by conjugate-spinning the above two kinds of polyolefins
into the form of side-by-side or sheath-and-core so that the
polyolefin having a lower melting point having the above
monoglceride incorporated therein can occupy at least one portion
of the fiber surface continuously in the length direction. In the
case of conjugate-spinning into the form of sheath-and-core, the
polyolefin having a lower melting point is used as the sheath
component. The ratio of both the components is preferably in the
range of 70/30 to 30/70 (ratio by weight). If the ratio of the
polyolefin having a lower melting point is less than 30%, the
resulting product obtained by heat-treatment has an insufficient
adhesion strength between the fibers thereof, while if the ratio of
the thermoplastic resin having a high melting point is less than
30%, the strength of the fibers themselves is insufficient. Thus,
the strength of the resulting product is insufficient in either of
the cases.
EXAMPLE
The present invention will be described in more detail by way of
Examples and Comparative examples. The definitions of the technical
terms and the test method of the physical properties employed in
these examples are described as follows:
Spinnability: a product which causes single fiber break once or
more for 10 minutes is regarded as bad and designated by a symbol
of x, and a product which causes single fiber break less than once
for 10 minutes is regarded as good and designated by a symbol of
o.
Fiber strength: measured at a gripping distance of 20 cm and at a
tensile rate of 20 cm/min. according to the testing method for
tensile strength of JIS L1013 (testing method for chemical fiber
filament yarn); and a product having a break strength of 2 g/d or
more was regarded as good and designated by a symbol of o and a
product having a break strength less than 2 g/d was regarded as bad
and designated by a symbol of x.
Charging properties: making up sample staple fibers into a web by
means of a roll carding machine and measuring the static voltage of
the web just after having left a doffer roll by means of a
collecting type potential measurement instrument (room temperature
20.degree. C.; humidity: 65%). A product having a static charge
exceeding 1.2 KV was wound around a cylinder or a doffer roll and
hence not suitable to practical use.
Bubbling properties: a sample filter was set to a filtration
tester, followed by passing water through the tester at a rate of
2,000 l/hr, collecting the first filtrate water (50 ml) in a 200 ml
graduated test tube, plugging the tube, shaking it one hundred
times and allowing it to stand for one minute. A product in the
case where bubbles are still remaining at that time was regarded as
bad.
Filtering test: a sample filter was set to a filtration tester,
attached to a stock solution tank, followed by passing water
through the filter at a rate of 2,000 l/hr adding active carbon
(Shirasagi C.RTM.; 43 microns or less, 80%) (0.5 g), polishing
finely-divided powder (FO #1200 (tradename); 5 to 15 microns, 90%)
(1 g) and carborundum (#220; 35 to 100 microns, 90%) (0.5 g),
thereafter taking 100 ml of the resulting filtrate and collecting
passed particles on a precise filter paper by suction filtration.
The particle diameter was measured by a microscope and the largest
particle diameter was recorded. Filterability is defined as the
adaptability of a liquid-solid system to filtration. The system is
not filterable if it is too viscous to be forced through a filter
mediam.
EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLES 1 TO 4
A high density polyethylene (melt flow rate 25, g/min , 190.degree.
C.) and the respective surfactants of the kinds and quantities
shown in Table 1 were fed into a first extruder, and a crystalline
polypropylene (melt flow rate 35, g/min , 230.degree. C.) was fed
into a second extruder, followed by conjugate-spinning by means of
a conjugate spinning die of side-by-side type (hole number: 100),
the extrusion rate and the extrusion temperature of both the
extruders being 6,000 g/hr and 250.degree. C., respectively, to
obtain undrawn filaments of 60 d/f. These undrawn filaments were
drawn to 3.2 times the original length, followed by subjecting the
resulting filaments to mechanical crimping of 12 crimps/25 mm and
cutting to a cut length of 64 mm to obtain staple fibers of 19
d/f.
The staple fibers were made up into a web having a basis weight of
20 g/m.sup.2 and a width of 800 mm by means of a roll-carding
machine, followed by sending this web horizontally, while heating
it successively from its end to 140.degree. to 150.degree. C. by
means of a far infrared rays heater, winding up the resulting web
by the length of 48 meters in a state where only the polyethylene
was melted, around the core of a stainless steel pipe (outer
diameter: 30 mm, weight: 4 Kg/m), under a pressure of its own
weight of the wound materila, cooling and cutting, to obtain a
hollow, cylindrical, formed product having a length of 250 mm, an
outer diameter of 70 mm and a weight of 240 g. This formed product
was used as a filter element and its bubbling properties and
filtering properties are tested. The tested results are shown
together in Table 1.
EXAMPLES 6 AND 7
Example 1 was repeated except that only the fineness of the
filaments was varied, to examine spinnability, fiber strength,
charging properties, bubbling properties and filtering properties.
These test results are shown together in Table 1.
COMPARATIVE EXAMPLES 5 and 6
Using the same polypropylene and polyethylene as in Example 1 but
without adding any surfactant to the polyethylene, conjugate
spinning of side-by-side type was carried out as in Example 1 or
Example 7, attaching polyoxyethylene adduct of sorbitan-monooleate
as a spining oil onto the resulting conjugate fibers (0.2% by
weight), to obtain staple fibers of 19 deniers (Comparative example
5) and 3 deniers (Comparative example 6). These staple fibers were
treated as in Example 1 to prepare hollow, cylindrical, formed
products. The test results are shown together in Table 1.
TABLE 1
__________________________________________________________________________
Static electricity Added Spinn- Fiber Fineness generated in
Bubbling Filterability Surfactant amount (%) ability strength (d/f)
carding (KV) (ml) (.mu.m)
__________________________________________________________________________
Ex. 1 Stearic acid monoglyceride 3 .smallcircle. .smallcircle. 19
0.8.about. 1.2 0 50 Ex. 2 " 5 .smallcircle. .smallcircle. 19
0.5.about. 1.0 0 50 Ex. 3 " 10 .smallcircle. .smallcircle. 19
0.4.about. 0.8 0 50 Ex. 4 " 5 .smallcircle. .smallcircle. 19
0.5.about. 1.1 0 50 Ex. 5 Oleic acid monoglyceride 5 .smallcircle.
.smallcircle. 19 0.6.about. 1.1 0 50 Ex. 6 Stearic acid
monoglyceride 5 .smallcircle. .smallcircle. 6 0.5.about. 1.0 0 10
Ex. 7 " 5 .smallcircle. .smallcircle. 3 0.5.about. 1.0 0 5 Comp.
Stearic acid monoglyceride 1 .smallcircle. .smallcircle. 19
5.about. 10 *2 -- -- ex. 1 Comp. " 13 x x -- -- -- -- ex. 2 Comp.
Sorbitan monooleate.POE 0.25 .smallcircle. .smallcircle. 19
10.about. 20 *2 -- -- ex. 3 Comp. No addition 0 .smallcircle.
.smallcircle. 19 20.about. 25 *2 -- -- ex. 4 Comp. Sorbitan
monooleate.POE *1 .smallcircle. .smallcircle. 19 0.05.about. 0.1 40
50 ex. 5 Comp. Sorbitan monooleate.POE *1 .smallcircle.
.smallcircle. 3 0.05.about. 0.2 40 5 ex. 6
__________________________________________________________________________
Footnote *1: Oiling agent attached 0.25% by weight. *2: Carding
passage, bad.
Apparent from the data shown in Table 1, the hot-melt adhesive
conjugate fibers having a specified surfactant incorporated
therein, according to the present invention, have sufficient
spinnability and low charge even when no surfactant is applied to
the fibers, and when a formed product obtained from the above
fibers is used as filters, no bubbling occurs in the filtrate and
also similar ability of retaining fine particles to that
conventional product is attained. Whereas, fibers having no
surfactant incorporated thereinto have a strong charge, and it is
difficult to form them into a web or obtain a formed product, while
fibers having a surfactant incorporated therein in excess is
inferior in spinnability. Further, fibers having a surfactant
applied thereonto give a product having an intense bubbling
properties of the filtrate, and cannot be applied to practical
use.
* * * * *